Modulation system for radio transmission apparatus



MODULATION SYSTEM FOR RADIO TRANSMISSION AEPARATUS Filed July 5, 1921 c v F #MWL- i 11mm-ef i Ail, s

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OF LGNEUN, ENGLND.

museum 'ille'i fully 5, i321, Serie No. @132,5255, and in @rest Britsiii suggest 1i), 15%.

This .invention if'eiuies to signaling sysiems, purticuliiriy rudio signaling systems. The invemlion is pm'tieulzii'ly concerned with .vli'eless 'erelglsmizting systems sind in part provides e A'system of ruoli@ telephony or .other oi'm of signaling in which am alternating o1' oseilleting'eurient is modulated. Tliermionio mnpiilieis having grids lieve previously been used am ible eoncluetois but the p1-osent. invention uses ifeeieis for el like purpose. The hes preferably uiiileierel, eoeflueiviy but muse lieve esymmietifoel 'conductivity'. Various types of reoiie' suiebie lout i prefer to use two-oieoeiocle *veiyes oi' eleeon discharge devices The scope of the invention wili Aoe .moi-e elem-Ly sees iii'om 'the cleseip'hions which :follown i' s two-electrode.Valve be eoiiif-.eee iii Wiili e, @Quiricol of highn iesueney eeei'gy :io-@l source 'eleclzo .motive ioiee, iie aumentpessed liifough the valve 'will dope-mi .egelyom 'mies of the seid eleciomoiye 'liooe if this is so oomiieeed time elle pisse of lle vulve is meile 'very' negewe ehe veli/e xviii pees no ou'ren; all. this negei'lve voltage be .me-.ile less d .ui ehe amplitude of elle oscillations supplieal "oy elle high-fifequeooy "elle valve will oonluo: en@ die entrees tlii'ougii is will depend Within limi-s om die siesdy 'voiage ayipliefi 'to the piste of the 'valve Eff, is pioposefi to veiy iliis vol'age 'oy the moiii'lzxtoi: which be e microphone and ii" may be desirable so ooiiple the seid eirooit to en system so time she cmrems 'pesseisliiougli elle valve may loe communi cated to the antenne. oscillation ireneioi'mei wiil, usually loeile I'fifi-ble, the pii muy being in she valve 'circuit :mii the seeouelsry iu 'die eeiizil circuit, The' 'valve oirn Cuit i'iey lioWevf-:if9 be coupled iii this manoei' of any otleif to lie input sifie 'of .an emgoliyimg valve, @he output side oi which is coupled, directly or indiiectly to the en" tenne. Several smpliyiiig Valves may be used. in 'this way Likewise ehe modulating potentiels may be ampliliecl.

Various other modifications sie possible without exceeding the scope of lio inves tion and will zeedily 0Com' io those experienced in the art. It is not proposed to limit the invention to *che use of valves singe any suitable feclil'iei' could oe employed. The inyeniion may aviso be used to modulate radio or' eoniol incoming energy in. e, reciio ie (zelver. A l

.ii oeslreol, .eveiel i'ectiers may be oonneced u: persllel, in wliioli ease the veives -can .be made progressively conductive lay telephony; Fig. i a, modification @i same embodying the use of en simplifies; emi. Figs. 5 and 6 further modilicstioiis employing; me i'ecfilying devices.,

shows e, somos oi varying oui-flens which in wireless transmission wiii oe if frequency Current. A 'h-ermiooio valve having mi .snode A and oeliode F is om neceecl in series Wih the source S, en oui-i: i oii'euii; being eonnecized soifoss fie termina A Y? 7. A somme of steady poseo-sisi E me anode of the reetii'iezr V s negozi* eotisl. The eufieioi;I ossseii by if W depend on the negative poeniiel ooL elle anode A. Fig. 2 will. :melee this clese. This tgm'e slioys *elle snode yoiegewmiode current curve Vf, V2, V3 of s, Wo-eleetroe valve. H we assume time the voltage ofi is suoiently negative to bring the @rest A of the positive halcyele to alle of the ouwe, the Valse will. conduct no corren@ plied by S, The steady negative potential on the :mode 'may ne celled the oase-line potential and iifftliis ease is represented by V..

L We lessen the baseline potentiel (new shown as V2), the positive haii-cycle A2 will more than overcome the negative potentiel V2 ami the representative point on ille ouwe will endeevoiito move up to V3. The

SLI:

lier V will now pass posiinive high-frequency I pulses which may be used in tlie output if# cuit. The magnitude of this output mirent will depend on the base-iine potentiel. The ou'put eircuit may be an impedance.

Fig. 3 shows the appliceion o1"- the invention io e, wireless telephone. The @Depot terminals Y, Z ae now part of en output 1recyuenoy trsnsormeiT LQ. A mic'roplione M and transformer T 1n series with the battery E enable die imode bese line potential 'to C is for luy-passing higlxequency suresnes. ih'e output from Y, Z is a high-equeiiey be varied. The condenser.

modulated one which will vary as the microphone 1s spoken linto. The baseline potential may loe anything from V to zero (Fier.

2) but will Ausually he V', ing` there is no output.

Fig. 4 shows a complete wireless teephone system in which the modulated potentials are amplitied by the valve Y2. The highfrequeuey currents are shown heiner induced into`the coupling circuit containingr the :modulatingv valve V. Although single rectitiers are'show'n, yet two such reetitiers Could be used'to conduct lioth lutti-cycleA of oscillating current. Fig. t'or example, shows the, use ot two rectitving valves in opposition. Cach' valve operates in the inannerl Shown in Si and 4. Fig. t' a lVhcn not speak- 'somewhat different arrangtanent which acts as a conductor ot' hoth halt' oscillations. The higlrfrequency current is `supplied hy S through a transformer lf. if.

In any of these arrangements several valves may be connected in parallel in the ordinatav way.

The invention is not intended to be con ned to transmitting systems. but may he used in receiving systems.

It is to he understood that the rectifier merely used as a variable conductor-and its rectiyingproperties are notv used in the normal way a rectifier is used in wireless signaling systems.

AS there are so many possibletinethods of carrying the invention into effect and turther applications of its use, it has been only thought necessary to give a few examples. /but it isnot desired to restrict the invention to'sneh examples.

Having thus-described the nature of the said invention and the hest means I know ot carrying?Y the saine into practical effect, claim rl. The method of modulating radio treqnency currents` according to which the uninodulated radio frequency currents are iinpressed upon a rect'it'yintr valve lmvingr t-wo electrodes only. the anode ot which has a steady negative potential and the value ot thi.q potential is varied hy impressed modulatineA waves,

2. ln a radio-sigmilling system, a inodu lating device comprising' a two-electrode rectifier` a source ot steady potential havingy its negative pole connected. with the anode of said rectitier. a source ot untnodulated radio frequency currents and a .source ott ntodulatiner currents connected in series with each other and with the .said rectifier and source ot steady potential. and a condenser directly bridgingr said sources ot lsteady potential and ot modulating currents.

3. A radio-signallingr system comprising a source otl radio frequency currents. a twoelectrodc 'valve rectifier in series therewith acting as avariahle conductor between an input and an output circuit` a source of steady potential in series with the rectifier and the source ot radio 'frequency currents and havingr its negative poley connected with the anode of said rectifier, an impedance in Series with the rectifier and with the `sources ot' radio frequency currents and o t steady potential, and means for Varying the potention across the rectifier nticrophonically.

In testimony whereof have signed my naine to this specifi cation.

` JOHN SCOTT-TAGGART. 

